The immunochemical properties of gastrointestinal mucin type glycoproteins will be examined to determine the potential of these glycoproteins as organ specific markers and to determine the extent of their immunological relatedness. Mucins have been isolated from the various anatomic regions of the gastrointestinal tract as well as from ovarian cystadenocarcinoma fluids. The mucins will be characterized as to amino acid and carbohydrate composition. Antisera have been prepared with each individual mucin preparation. The specific antibody will be purified by absorption and affinity procedures. The organ distribution (specificity) will be examined by immunohistochemical procedures employing normal adult tissues as substrates. A sensitive radioimmunoassay has been developed and is being employed for heterologous inhibition studies in order to examine immunochemical relatedness between individual mucin preparations. The potential role of the antigens as tissue markers will be analyzed by a retrospective study of biopsy specimens from individuals with benign and malignant disorders of both gastrointestinal and extragastrointestinal tissues.